package Template;

import java.util.Scanner;

/**
 * 浮点数二分算法模板
 */
public class floatBinarySearch {
    private static final double ESP = 1e-8;
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double num = sc.nextDouble();
        double left = -Double.MAX_VALUE;
        double right = Double.MAX_VALUE;
        while ((right-left)>ESP){
            Double mid = (right+left)/2;
            if ((mid*mid*mid)>=num){
                right=mid;
            }else {
                left = mid;
            }
        }
        System.out.printf("%.6f",left);
    }

}
